Method of and apparatus for cooling vulcanizing molds



sept. 19,1939. `M. MAHLER 2,173,588

METHOD OF AND APPARATUS FOR COOLING VULCANIZING MOLDS Filed Nov. 15, 19256 10 Je uber www I Patented Sept. 19, 1939 UNITED STATES PATENT OFFiCE METHOD OF ANDI APPARATUS FOR COOLING VULCANIZIN G MOLDS ark, N. J.

Application November 13, 1936, Serial No. 110,734

9 Claims.

This invention relates to new and useful improvements in cooling systems for tire retreading molds and contemplates an assembly by means of which hot water may be introduced in the mold subsequent to and immediately following the vulcanizing process, and the temperature of this hot water gradually lowered by co-mingling with cold water, permitting gradual cooling which will not injuriously affect the vulcanized product or the mold itself.

More specifically the invention contemplates the provision of hot and cold water tanks, each of which is connected to a pump, and through the pump to the retreading mold, with return means for the fluid from the mold to the tanks whereby a continuous circuit is provided, which circuit may be regulated as desired to obtain denite temperatures for the cooling process.

The system further contemplates the utilization of circuits, each of which is definitely controlled by suitable Valve means and some of which utilize partial sections of the conduits forming other circuits whereby complicated valves are eliminated and the operation of the mechanism faciiitated.

Another object of the present development is the provision of means for the introduction of cooling uid, at definite steps in the cooling operation, and the control of the cooling fluid from the mold into either or both hot and cold water tanks according to the temperature and according to the desires of the operator.

Other objects and features of the invention will more clearly hereinafter appear by reference to the accompanying drawing, specification and claims forming part of this application in which- Figure 1 is a plan View showing the apparatus, parts being broken away to more clearly illustrate the development.

Figure 2 is a section on line 2 2 of Figure 1.

Figure 3 is a section on line 3--3 of Figure l.

And Fig. 4 is a fragmentary sectional View showing one method of securing the fluid introducing members to the mold sections.

In the drawing a conventional tire retreading mold is shown and includes the lower section A supported on standards C and upper section B. A steam boiler or other source of steam supply is indicated at D and steam from this source is conducted through the pipe l and connections 2 and 3 to the mold sections A and B. The supply of steam from the steam boiler D is controlled by the valve 4. A return pipe 5 returns the vapors to the steam boiler D and this pipe' communicates with the upper and lower sections A and B of the mold by means of the branch pipes t and 1. The connections 2 and 6 which communicate with the supply and return pipes and the upper hinged mold section B are preferably formed from suitable lengths of hose or other flexible conduits, this being essential inasmuch as the upper section of the mold is swung upwardly away from the lower section A in positioning and removing a tire for the retreading operation. A valve 8 controls the passage through the return conduit 5.

The tanks E and F act as reservoirs for hot and cold water, the tank E being designed particularly for the cold water supply and the tank F for the hot water supply. The supply of hot water for the tank F is provided by means of the heater G, which is of conventional structure, and may be provided with suitable heating means such as the gas heater H, the latter being supplied with gas through the conduit 9 and the supply of gas being regulated by the thermostatically controlled valve illustrated at l. Pipe ll conducts the water from the tank F through the gas heater and returns it by means of pipe l2 back into the tank F. A valve lli is a check valve arranged in pipe Il for controlling the supply of water flowing into the heater G.

A cold water line I5 which may be connected to any suitable water supply or water main, conveys the water supply to the tanks E, F by means of branch pipes I6 and Il, each of which is provided with a Valve I8 for regulating the passage of the water therethrough. It will be noted that the branch pipes i6 and Il extend upwardly through the bottom of the tanks E, F and the branch pipe I6 has a lateral extension 20 whereby the water in the cold water tank E is discharged approximately at the center thereof.

A pump J operated by a suitable motor j is utilized for circulating the water from either or both of the tanks E, F into the two sections of the retreading molds A, B, and back into the respective tanks, as may be determined by the proper regulation of valve conduits hereinafter described.

The pump J is of a type that will draw air from the atmosphere through pipe K by suction. A conventional water gear pump of over 600 R. P. M. will perform this function. I have used a water gear pump of 1750 R.. P. M. with very satisfactory results.

The circulation from the tanks E, F to the mold sections, A, B includes the pump inlet pipe 22 which communicates with the branch pipes 23 and 24 which branch pipes are tapped into the base of the cold and hot water tanks E, F respectively. Pipes 23 and 24 are connected to the pipe 22 by the cross T shown in Fig. 2, said cross T having a bushing, shown cross-sectionally, through which the pipe K passes. Valves 25 control the discharge from these tanks into the pump. The discharge from the pump is by means of the pipe or conduit 25, branch pipe 28 and hose section 29 to the upper movable mold section B and branch pipe 2l of lower section A. Valves 36 are positioned in the branch pipes 2ll and 28 for regulating and controlling the passage of uid therethrough into the mold sections. The Water forced into the mold sections through pipe 26 is returned to the tanks E, F either or both as may be desired, by means of pipe 32, which is tapped into the steam lines I and 5, between the valves 4 and 8 and the mold, which sections of the steam line are in normal open communication with the two mold sections A, B. The pipe 32 discharges directly into the tank F and has a short branch pipe 33 discharging into the tank E. A valve 34 controls the passage of iiuid through the pipe 32 while the valves 35 and 36 control the flow through the two pipes discharging into the separate tanks E, F.

In use of the assembly the vulcanizing is produced by the utilization of steam from the steam boiler D introduced into the two sections oi the mold through pipe I and branch pipes 2 and 3. The condensed steam is returned through branch pipes 6 and 'i and return pipe 5. As heretofore stated I and 5 are controlled by the valves 4 and 8 and during the vulcanization process both of these valves remain open to provide an open circuit. After the vulcanization is completed the valves l and 8 are closed. The valves 34 and 35 are then opened permitting the discharge of any residue steam in the molds to escape to the tank F by virtue of the branch pipes 2, 3, 6 and "I, and the adjacent pipe sections l and 5. The valves 3Q are then opened and the pump is started. The valve 25 of pipe 24 is opened permitting the hot water to circulate from the hot water tank through the pump and into the mold sections. After the hot water has been pumped through the mold for a short time the valve 25 in the pipe 23 is gradually opened permitting a co-mingling of the cooler water from the tank E with the hot water from the tank F and this gradually tempered water is circulated by means of the pump in the same cycle as the hot water i. e., through pipe 22, pump J, pipe 25 and branch pipes 2-29. The Valve 25 of pipe 24 of the hot water tank is gradually closed permitting the rapid decrease in temperature by increasing the flow oi cold fluid from the tank E through the pipes 22 and 23. The cold water may be discharged entirely into the cold water tank by opening the valve 36 of the branch pipe 33 of the discharge may be both into the tanks E and F, depending upon the desire of the operator. In order to obtain a more eii'icient cooling action the valve I8 in the cold water line I5 may be opened to supply the necessary added amount of cold water for the pump. When the temperature of the mold has been lowered suiciently the valves 25 are closed and the pump permitted to continue its operation forcing the water remaining in the mold outward into the tanks, air being introduced for this operation through pipe K, pipe 22, pump J, pipes 23, 21 and 29, the mold and the pipe line 32.

A drain pipe 4B is provided and may be connected to a suitable sewer, this pipe having vertical extensions 4I and 42 into the tanks, which extensions extend upwardly to a point approximately the desired water level of the tanks, so that during the cooling operation surplus cooling :duid which may be introduced into the system by the opening of the valves IB will be automatically discharge and disposed of. Drain pipes 44 and 45 provided with suitable valves 4t are utilized in emptying the tanks when not in use or when repairs or cleaning of the system is considered desirable. These pipes under control of valves 6 open into the drain 40.

Water gauges 41 are illustrated arranged on the tanks for indicating the condition of the fluid therein. Obviously, during the utilization of the apparatus the automatically controlled heater G will function to retain the fluid in the tank F at the desired temperature. The pipe K opens to the atmosphere and connects with the pump circuit, the form of connection being illustrated in Figure 2.

In Figure 3 the novel type of connection is illustrated for permitting the discharge of water from the mold sections and through a section of the steam line I, and return 5. This connection comprises a cross T 49 having a connection 50, at the upper inside portion of which is the bushing 5I having the elongated tube, shown cross sectionally, fixed therein, said tube extending upwardly within line I to enable water, evacuated from the top and bottom sections of the mold, to flow upwardly through pipe 32 without crossresistance within T 69. The aperture in the tube enables any water which might settle in line I to drain off through connection 50.

Obviously, additional control valves and pipe connections can be added to the system if necessary, however, the present set-up is such as to enable a desirable operation. The use of check valve G9 in the condensed water return line 5 is an illustration of the type of additions to the system which may be deemed advisable under unusual working conditions.

In Fig. 4 there is shown, cross-sectionally, the manner in which the members 2l and 29 are tapped into sections A and B, viz. by providing the ends of said members within the sections with closed nipples 60 having transverse apertures lil-6I to diffuse water in jets, in opposite directions, longitudinally and uniformly throughout the sections.

In retreading tires by the use of heavy cast molds to which my invention relates, it is customary in the art to thoroughly dry the tire before inserting the tire in the mold. To thoroughly dry the tire it is necessary to remove the breaker strip, thus seriously weakening the tire. When the tire is thought to be thoroughly dry, it is inserted cold, in the preheated mold, where the shock of sudden contact of the cold tire with the hot mold causes irregular curing. No matter how much care is exercised in pre-drying a tire, some moisture usually remains. Where, as is Customary in the art, the tire is relieved of its internal pressure after vulcanization and is removed from the mold while both tire and mold are hot, any moisture in the tire will rip the tire apart, representing a serious loss to the retreading plant.

My arrangement obviates the drying of the tire before its insertion into the mold. Thus the original strengthening breaker strip is kept in the tire, the tire being merely buffed to remove the glossy surface; then the dull parts of the tire are rubberized and the rubber cement is allowed to dry until it becomes sticky. I then apply the new rubber and place the tire, which is cold, into the mold. 'Ihe temperature of the mold is gradually raised and the tire is thereby gradually heated to vulcanization. After vulcanization, the heating mold is gradually cooled, the tire likewise being gradually cooled. The tire is relieved of its internal air pressure. Thus the tire is cooled and any moisture in the tire remains in its liquid form instead of turning into steam and damaging the tire. The tire is removed from the mold in cool condition, with no danger of internal defects due to moisture.

My invention is adapted for use with any of the various types of heavy molds on the market for retreading tires. It results in economy of operation, in greater earnings and more accurate work in the retreading shop.

What I claim as new and desire to secure by Letters Patent is:

1. The method of cooling a mold which has attained vulcanization temperature by being filled with a heating medium, which consists in discharging the heating medium from the mold, flushing the mold with a heated medium in continuous circuit through the mold, progressively cooling the last named medium in its circuit prior to its passage through the mold to progressively cool the mold and nally flushing the mold with a non-liquid medium to evacuate the mold in preparation for the next vulcanization operation.

2. The method of claim 1 wherein the nonliquid medium is commingled with the heated medium in the circuit of the latter until the latter has been completely evacuated from the mold.

3. The method of claim l wherein the nonliquid medium consists of air introduced into the circuit of the heated medium.

4. The method of cooling a mold which has attained vulcanization temperature by being filled with a heating medium, which consists in discharging the heated medium from the mold, ushing the mold with a heated medium commingled with air in continuous circuit through the mold, progressively cooling the last named medium in its circuit prior to its passage through the mold to progressively cool the mold, and

nally flushing the mold by pumping air therethrough.

5. The method of claim 4 wherein the heated medium is heated water.

6. The method of cooling a heavy cast mold which has attained vulcanization temperature, which consists in flushing the mold with heated water in continuous circuit therethrough, progressively cooling the Water in its circuit prior to its passage through the mold to progressively cool the mold, and finally discharging the water from the mold.

7. The method of claim 6 wherein air means is used to discharge the water from the mold.

8. An apparatus for cooling a retreading mold having chambers provided with steam inlet and outlet pipes and control Valves therefor, comprising a hot water tank, a cold water tank, a pump, an intake pipe for said pump, and an outlet pipe for said pump, connections between the hot and cold water tanks and the pump intake pipe, control valves for said connections, a connection between said pump outlet pipe and each of said steam chambers, control valves for said connections, and water return pipes connecting the steam inlet and outlet pipes with said tanks.

9. An apparatus for cooling a retreading mold having steam chambers comprising steam inlet and outlet pipes and control valves therefor, a hot water tank, a cold Water tank, a pump, an intake pipe for said pump, and an outlet pipe for said pump, connections between the hot and cold water tanks and the pump intake, control valves for each of said connections, a connection between said pump outlet and each of said steam chambers, control valves for said connections, water return pipes connecting the steam inlet and outlet pipes with said tanks, valves for each of said connections, a Water supply for each of said tanks, control valves for each of said water supply tanks, drain pipes for each of said tanks and control valves therefor, a waste pipe, connections between said tanks, drain pipes and said waste pipe, overflow pipes for said tanks and connections between said overflow pipes and said waste pipe, a water heater in circuit with said hot water tank, and automatic means for regulating said water heater for maintaining the water in said tank at a predetermined temperature.

MAX M AHLER. 

